(MAC address and serial number masked)
The lines from rndis_host and usbcore are what matters the most, here.

The phone has no problem, or it wouldn't work on Debian. The problem has to be in my configuration.
Debian Squeeze's kernel is 2.6.32. It's the vanilla kernel from Debian.
My gentoo kernel was compiled by me.
I activated every module recommended in the above links: